As the Red Army pushed the front westward, local Partisan units often became bolder in their attacks. A group of partisans from the area near the Ukraine town of Vinnitsa dynamited the eastbound railroad tracks, derailing a German munitions train bound for the front. The partisans attacked the train, killing 150 German soldiers before disappearing into the woods. Soldiers from the munitions train stopped a troop train filled with veteran Wehrmacht soldiers, new recruits and members of the Grossdeutschland division returning from leave. A troop of about two thousand moved into the woods to pursue the partisans. The Germans learned that a nearby factory in the woods served as a command center for the partisans. An SS Hauptman led about a hundred men into the woods to storm the factory.